Greek for the murky lower atmosphere — distinguished from the bright 'aether' above — and via Italian gave us 'malaria' (bad air).
The invisible gaseous substance surrounding the earth, a mixture mainly of oxygen and nitrogen.
From Old French 'air,' from Latin 'aer,' from Greek 'aer' (ἀήρ), meaning air, mist, haze, or the lower atmosphere as distinct from the upper sky ('aither'). The Greek word is of uncertain ultimate origin; some connect it to PIE *h₂weh₁- (to blow), though this is debated. In early Greek usage, 'aer' referred specifically to mist or fog — the murky air close to the ground — while 'aither' denoted the clear, bright upper sky. Aristotle formalized 'aer' as one of the four classical elements. The word entered Latin largely
'Malaria' literally means 'bad air' — from Italian 'mala aria.' Before germ theory, people believed the disease was caused by noxious vapors rising from swamps. They were wrong about the mechanism but right about the location: mosquitoes that carry malaria breed in exactly those swampy, misty places that produce 'bad air.'